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Chapter 8 (mean drift velocity (A is the cross sectional area of the…

- - - - so electrons must move faster through narrower wires
        
        mean drift velocity is inversely proportional to the cross-section are of the wire
  - - - n of conducters is very high n (around 10^28 m^-3)
      - n of insulators is very low
      - n of semiconductors is lower, with number densities around 10^17 m^-3
- - - - If a positive electrode (anode) and a negative electrode (cathode) are placed in the solutions, ions are attracted to the electrodes
        
        the anions move towards the anode
        
        the movement of the ions is a flow of charge (an electric current)
        
        When the Na^- ions reach the cathode they accept and electrode
        
        when the Cl^- ions reach the anode they donate an electron
        
        Allowing for the flow of electrons in the circuit
        
        the cations move towards the cathode
- - - - free electrons are attracted to the +Ve end of a wire, and repelled from the -ve end of a wire which is how we can make electrons move through a metal. (wire is metal) (conduction using delocalised electrons)
        
        a larger current may be due to
        
        a greater number of electrons moving past a given point each second (e.g. larger cross-sectional area)
        
        same number of electrons moving faster through the metal
- - - - 10A in = 10A out
        
        7A in = 7A out
    - - Σ = sum of (sigma)
        
        is based on the conservation of charge where the charge is the produce of the current and the time.
        
        as charge cannot be destroyed the charge carriers entering a point in a given time must equal the total number of charge carriers leaving that same point during that time